i wanting to make a custom transformers Optimus Prime 20th Anniversary trailer and i was wondering what scale he is i think he is 1:24 but im not sure and has anybody else made one on here if so any pics so i can get a idea for it and thanks for the help

Buy MP-04. It has the trailer.

It's also retardedly expensive....

I'd venture a guess at 1:20 to 1:24...I don't really think he's in any actual scale. I know that I bought a scaled trailer some time ago and modded it to fit him. It's a bit off but it's close enough and I know it was in the area I mentioned above. You could try buying one of the (Newbright?) scaled trailers at TRU and trying it out. If it doesn't fit, take it back and get one in a different scale as they make several. They're in the cheapy dicast aisle on the other side of the HotWheels.